This system is a strictly confidence-based resource categorisation and estimation procedure. The mineral resource is sub-divided into areas of greater or lesser confidence in the estimate, ultimately based both on the geo-statistical characteristics of the ore body and on the proximity, type and amount of geological and sampling data that might have been used to extrapolate values into particular blocks. Different geo-statistical techniques are applied as appropriate and the quality of the estimates is tested by cross-validation and reconciliation.

Owing to differences in the definition of resources and reserves, the mineral resources segment has been divided into four separate sections:

South African operations
Other African operations
American operations
Ergo

Abridged definitions
Mineral resource: a mineral deposit that may eventually be economically and legally extracted. Mineral resources reported in this document are restricted to the portion included in the life of mine plan and are sub-divided into:

Inferred mineral resource: a mineral resource where sampling and other data are insufficient to permit interpretation of the geological framework or to enable prediction of the continuity of mineralisation with any degree of confidence. Indicated mineral resource: the spacing of sampling and geological data points affords a degree of confidence high enough to give a reasonable indication of continuity of mineralisation. Measured mineral resource: the sampling and geological data points are spaced such that continuity of geological character and grade may be estimated with a high degree of confidence.

Mineral reserve: that part of a mineral resource which could be technically, economically and legally mined under conditions existing at the time of reporting.

Mineral reserve (South African operations): reflects the payable component of the mineral resource as calculated under conditions pertaining in December 1998. It should be noted that these conditions will change and therefore pay limits will change in the future. In addition, the long-range mining plan will mine a mixture of 'payable reserve' and 'marginal resource'. Mineral reserves are sub-divided into:

Probable mineral reserve: that part of the indicated mineral resource above a pay limit calculated in December 1998.

Proved mineral reserve: that part of the measured mineral resource above a pay limit calculated in December 1998.

The tonnages quoted as reserves and/or resources are in situ and are estimated over a stoping width. Grades are also in situ and estimated over a stoping width with no allowance being made for additional dilution or gold loss.

It follows from these definitions that there are components of the mineral deposit that are unlikely to be economically and legally extracted in the foreseeable future and which are therefore not reported as part of the mineral resource.

Mineral reserve (Other African operations): reflects the estimated tonnage and grade as delivered to the treatment facility and includes allowances made for additional dilution or gold loss. Mineral reserve (Ergo): reflects the estimated tonnage and grade of the mineral resource in the slimes dams and sand dumps, or portions thereof, that are currently technically and economically treatable.

Total mineral reserves ? (proved plus probable)

*Excludes Driefontein

Other African operations

Reconciliation
The year on year reconciliation of the total mineral resource (measured plus indicated) is reflected below:

South African underground operations*

* Excludes Driefontein

Other African operations

The estimated life of mine milling potential at a starting average gold price in January 1999 of R58 400 per kilogram or $298 per ounce with declining annual throughput is set out below. The estimate is based on data and assumptions which are continually being reviewed and milling potential could change significantly.

* Excludes Driefontein